The Transparent Interconnection of Lots of Links (TRILL) protocol is a routing protocol based on link state computation on a layer 2 network, a device running the TRILL protocol is referred to as a routing bridge device (RB), and a network including RBs is referred to as a TRILL network (TRILL Campus). Large layer 2 networking can be implemented by using TRILL, which overcomes disadvantages such as low utilization and long convergence time of a conventional layer 2 network.
A conventional layer 2 native Ethernet can access a TRILL network, and to improve reliability of access to the network, a multi-homing access manner is usually used. If a topology of a network accessed by a terminal (End Station, ES) is switched, an RB accessed by a local terminal device may be switched, and if a MAC forwarding entry that is on a remote RB and is used for storing a correspondence between a MAC address and a nickname of an ingress RB cannot be cleared in time, the remote RB may perform forwarding by using an old MAC forwarding entry, which causes a forwarding failure.